Net Income (Loss) per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Numerator:
Net income attributable to AXT, Inc.	$ (3,621)	$ (5,823)	$ (5,089)	$ (3,348)	$ 1,341	$ 5,759	$ 5,546	$ 3,165	$ (17,881)	$ 15,811	$ 14,575
Less: Preferred stock dividends									(177)	(177)	(177)
Net income (loss) available to common stockholders									$ (18,058)	$ 15,634	$ 14,398
Denominator:
Denominator for basic net income (loss) per share - weighted-average common shares									42,643	42,104	41,367
Effect of dilutive securities:
Denominator for dilutive net income (loss) per common shares									42,643	42,715	42,720
Basic net income per share:
Basic	$ (0.09)	$ (0.14)	$ (0.12)	$ (0.08)	$ 0.03	$ 0.14	$ 0.13	$ 0.07	$ (0.42)	$ 0.37	$ 0.35
Diluted net income per share:
Diluted	$ (0.09)	$ (0.14)	$ (0.12)	$ (0.08)	$ 0.03	$ 0.13	$ 0.13	$ 0.07	$ (0.42)	$ 0.37	$ 0.34
Common stock options
Effect of dilutive securities:
Effect of dilutive securities (in shares)										333	803
Weighted-average shares:
Securities excluded from diluted net income (loss) per share as the impact is anti-dilutive (in shares)									1,198	220	21
Restricted stock awards
Effect of dilutive securities:
Effect of dilutive securities (in shares)										278	550
Weighted-average shares:
Securities excluded from diluted net income (loss) per share as the impact is anti-dilutive (in shares)									1,258	291	118